by Kate Russell

What does ‘substantial’ mean?

The adverse effect on normal day-to-day activities must be a substantial one. It must be more than a condition which may be considered to be minor or trivial.

Factors to consider

1. Time to carry out an activity

The time taken by a person with an impairment to carry out a normal day-to-day activity should be considered when assessing whether the impairment’s effect is substantial. Compare it with the time it might take a person who does not have the impairment to complete an activity.

Another factor to be considered is the way in which a person with that impairment carries out a normal day-to-day activity compared with the way that the person might be expected to carry out the activity if he does not have the impairment.

2. Cumulative effects of the impairment

Taken in isolation, an impairment might not have a substantial adverse effect on a person’s ability to undertake a particular day-to-day activity, but its effects on more than one activity, taken together, could result in an overall substantial adverse effect.

For example, a person whose impairment causes breathing difficulties may, as a result, experience minor effects on the ability to carry out a number of activities, such as getting washed and dressed, preparing a meal, or travelling on public transport. But taken together, the cumulative result would amount to a substantial adverse effect on his ability to carry out these normal day-to-day activities.

3. Environmental factors

Environmental conditions may exacerbate the effect of an impairment. Factors such as temperature, humidity, lighting, the time of day or night, how tired the person is, or how much stress he is under, may have an impact on the effects. When assessing whether adverse effects are substantial, the extent to which such environmental factors are likely to exacerbate the effects should also be considered.

The focus here is on what the worker cannot do or can only do with difficulty. Just because the employee can carry out a number of day-to-day activities, this doesn’t mean that he is not substantially affected.


G was a paranoid schizophrenic. He coped adequately with living alone. However, his evidence was that he suffered from hallucinations, had difficulty concentrating and misinterpreted the words of his work colleagues in a paranoid way. In addition, he was unable to hold a normal conversation, behaved strangely at times and had significantly impaired concentration.

The EAT found that the symptoms of his illness impaired his ability to concentrate and communicate and that did affect his ability to carry out normal, day-to-day activities substantially.

4. Effects of behaviour

In deciding what is substantial, consider how far a person can reasonably be expected to modify his behaviour to prevent or reduce the effects of an impairment on normal day-to-day activities. If he can reasonably be expected to behave in such a way that the effect of the impairment doesn’t have a substantial adverse effect on his ability to carry out normal day-to-day activities, he would no longer meet the definition of disability. For example, when considering modification of behaviour, it would be reasonable to expect a person who has back pain to avoid extreme activities, such as parachuting. It would not be reasonable to expect him to give up, or modify, more normal activities that might exacerbate the symptoms, such as moderate gardening, shopping, or using public transport.

You also have to take into account a situation where a person avoids doing things which, for example, cause pain, fatigue or substantial social embarrassment or avoids them because of a loss of energy and motivation. It would not be reasonable to conclude that a person who employed an avoidance strategy was not a disabled person. In determining a question as to whether a person meets the definition of disability, it is important to consider the things that a person cannot do, or can only do with difficulty, rather than focusing on those things that a person can do.

For example, a woman with a persistent stammer uses coping strategies to manage her condition, such as avoiding using the telephone, not giving verbal instructions at work, limiting social contact outside her immediate family, and avoiding challenging situations with service providers. It may not be readily obvious that she has an impairment which adversely affects her ability to carry out normal day-to-day activities. In determining whether she meets the definition of disability, you should consider the extent to which it is reasonable to expect her to place such restrictions on her working and domestic life.